Allison was born and raised in the small rural farming town of Edinboro, Pennsylvania, approximately 20 miles south of Lake Erie. Her discovery at the age of 14 in a doctor's office by a model scout/agent marked the beginning of her modeling career in Toronto, with subsequent summers spent in Manhattan. Following her high school graduation, Allison pursued her passion for theatre by studying at the University of Pittsburgh, where she also spent a semester abroad studying theatre in London.
Upon completing her studies, Allison relocated to New York City, where she landed roles in several Off Broadway productions. Her breakthrough in television came with small parts in 'Rescue Me' opposite Dennis Leary and 'Stella' with Michael Ian Black and Michael Showalter. As her career progressed, Allison began dividing her time between New York and Los Angeles.
In 2008, Allison starred alongside Michael Madsen and Dennis Hopper in Quentin Tarantino's 'Hell Ride', and later that year, she appeared opposite Robert Downey Jr. and Gwyneth Paltrow in Jon Favreau's 'Iron Man'. In 2010, she starred in the indie film 'Bloomington', which quickly gained a cult following. Her subsequent roles included a recurring part starring opposite David Duchovny on Showtime's 'Californication', followed by a series regular role opposite John Schneider and Tika Sumpter on Tyler Perry's 'The Haves and the Have Nots' on OWN.